A conventional paper guiding mechanism for a printer is shown in Japanese Laid-Open Utility Model Application No. Sho 59-67255.
The mechanism as disclosed has a lower casing having a lower guide in which a printer body having a print head and paper feeding tractors are mounted, and an upper casing having an upper guide which is connected to the lower casing by a connecting means such as hinges. When the upper casing is closed against the lower casing, a paper guide path for guiding paper past the printer is formed between the upper guide of the upper casing and lower guide of the lower casing. The paper is supplied to the lower casing through a supply gate which is formed in a bottom surface of the lower casing, is engaged with paper feeding tractors positioned along the paper guide path, and is discharged from a discharge port which is formed in the rear surface after being fed along the guide path.
In such a conventional paper guide mechanism as described above, the upper casing forming the upper side of the paper guide path is mounted so as to be able to be opened and closed relative to the lower casing containing the printer body forming the lower side of the paper guide path.
At the start of operation, paper is inserted into the printer body while the upper casing is opened, and the paper guide path is formed only when the upper casing is closed.
Therefore, the upper side of the paper guide path which is formed by the upper casing has to be shaped for guiding the leading end of the paper along the paper guide path when the upper casing is closed and to avoid causing a paper jam due to folded paper at the time of closing the upper casing.
However, because the upper side of the paper guide path is formed integrally with the upper casing, these two functions are inadequately carried out.
For example, in a conventional paper guide mechanism as shown in FIGS. 4(a)-4(d), when the upper casing 2 is closed when the paper 1 to be fed past the printer body projects upwardly above the lower side of the paper guide path, as shown in FIG. 4(a), the leading end of the paper is folded back in the direction opposite to the paper feeding direction as shown in FIG. 4(b), because the angle of the paper 1 to the upper side of the paper guide path is unsuitable.
Although the paper 1 may sometimes be guided in the proper direction and caused to enter the paper guide path when the operation of the printer starts, if the paper is thin or limp, it may be wrinkled up due to the folding back and the paper guide path clogs, as shown in FIG. 4(c). This is because the angle of the upper side of the paper guide path is unsuitable and the dimension of the path in the thickness direction of the paper is too large.
In order to overcome such defects, the shape of the upper side of the paper guide path can be formed as shown in FIG. 4(d) for reducing the dimension of the said thickness direction when the upper casing 2 is closed. However, when this is done, it often happens that the leading edge of the paper 1 does not enter the paper guide path properly when the upper casing 2 is closed.